Never decode the favicon in FaviconUtil::SelectFaviconFramesFromPNGs() when the desired size is 0

chrome/browser/favicon/favicon_util.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/favicon/favicon_util.h"
 
 #include "chrome/browser/history/select_favicon_frames.h"
 #include "chrome/common/favicon/favicon_types.h"
 #include "skia/ext/image_operations.h"
 #include "third_party/skia/include/core/SkBitmap.h"
@@ skipping 14 matching lines @@
 // or decoding the bitmap data.
 std::vector<gfx::ImagePNGRep> SelectFaviconFramesFromPNGsWithoutResizing(
     const std::vector<chrome::FaviconBitmapResult>& png_data,
     const std::vector<ui::ScaleFactor>& scale_factors,
     int favicon_size) {
   std::vector<gfx::ImagePNGRep> png_reps;
   if (png_data.empty())
     return png_reps;
 
   // A |favicon_size| of 0 indicates that the largest frame is desired.
-  if (favicon_size == 0 && scale_factors.size() == 1) {
+  if (favicon_size == 0) {
     int maximum_area = 0;
     scoped_refptr<base::RefCountedMemory> best_candidate;
     for (size_t i = 0; i < png_data.size(); ++i) {
       int area = png_data[i].pixel_size.GetArea();
       if (area > maximum_area) {
         maximum_area = area;
         best_candidate = png_data[i].bitmap_data;
       }
     }
     png_reps.push_back(gfx::ImagePNGRep(best_candidate,
-                                        scale_factors[0]));
+                                        ui::SCALE_FACTOR_100P));
     return png_reps;
   }
 
   // Cache the scale factor for each pixel size as |scale_factors| may contain
   // any of GetFaviconScaleFactors() which may include scale factors not
   // supported by the platform. (ui::GetScaleFactorFromScale() cannot be used.)
   std::map<int, ui::ScaleFactor> desired_pixel_sizes;
   for (size_t i = 0; i < scale_factors.size(); ++i) {
     int pixel_size = floor(favicon_size *
         ui::GetScaleFactorScale(scale_factors[i]));
@@ skipping 70 matching lines @@
   // - Sync does a byte-to-byte comparison of gfx::Image::As1xPNGBytes() to
   //   the data it put into the database in order to determine whether any
   //   updates should be pushed to sync.
   // - The decoding occurs on the UI thread and the decoding can be a
   //   significant performance hit if a user has many bookmarks.
   // TODO(pkotwicz): Move the decoding off the UI thread.
   std::vector<gfx::ImagePNGRep> png_reps =
       SelectFaviconFramesFromPNGsWithoutResizing(png_data, scale_factors,
           favicon_size);
 
+  // SelectFaviconFramesFromPNGsWithoutResizing() should have selected the
+  // largest favicon if |favicon_size| == 0.
+  if (favicon_size == 0)
+    return gfx::Image(png_reps);
+
   std::vector<ui::ScaleFactor> scale_factors_to_generate = scale_factors;
   for (size_t i = 0; i < png_reps.size(); ++i) {
     std::vector<ui::ScaleFactor>::iterator it = std::find(
         scale_factors_to_generate.begin(),
         scale_factors_to_generate.end(),
         png_reps[i].scale_factor);
     CHECK(it != scale_factors_to_generate.end());
     scale_factors_to_generate.erase(it);
   }
 
@@ skipping 43 matching lines @@
     int desired_size) {
   std::vector<gfx::Size> sizes;
   for (size_t i = 0; i < bitmaps.size(); ++i)
     sizes.push_back(gfx::Size(bitmaps[i].width(), bitmaps[i].height()));
   std::vector<size_t> selected_bitmap_indices;
   SelectFaviconFrameIndices(sizes, scale_factors, desired_size,
                             &selected_bitmap_indices, NULL);
   DCHECK_EQ(1u, selected_bitmap_indices.size());
   return selected_bitmap_indices[0];
 }